It is the engineering control that works alongside respirators rather than replacing them.
Source extraction captures fume at the arc. A fume extraction gun or a flexible extraction arm positioned close to the weld captures most of the plume with far less airflow than ventilating the whole shop. The capture distance matters — an extraction hood more than about 12 in from the arc captures very little, because the plume disperses and rises.
Shop-wide ventilation and air filtration handle what source extraction misses. Downdraft tables pull fume down through the work surface, which suits bench work. Ambient air cleaners with HEPA and activated carbon filtration remove particles and odour but do not replace source capture in a heavy welding environment.
Filter selection and maintenance determine whether the system keeps working. A loaded filter reduces airflow and capture velocity, which is invisible from the outside. Filter life depends on the duty cycle and on the amount of oil and particulate in the air, and replacement intervals should follow the manufacturer's guidance rather than a visual check.
